mx.granverano.com has no NS records.
NS records for this zone are defined at granverano.com.
NS records for this zone are defined at granverano.com.
Question and response
Question
dig mx.granverano.com. NS
Answer
The response has no answer records.
Authority
granverano.com. 3600 SOA dns.granverano.com. hostmaster.granverano.com. 1913376681 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0